Detection of tau phosphorylated at threonine 231 in cerebrospinal fluid of Alzheimer's disease patients.

A new sandwich ELISA is described which shows specificity for tau phosphorylated at threonine 231 and preferentially reacts with Alzheimer's disease (AD) brain extracts relative to other dementias. This assay was used to analyze 58 antemortem cerebrospinal fluid samples. Twenty-three of 27 AD samples (85% sensitivity) yielded signals greater than the cutoff, while only one of 31 non-AD samples (97% specificity) were greater. This indicates that detection of phosphotau in cerebrospinal fluid with this sandwich ELISA could prove useful in the diagnosis of AD.